This disclosure relates to a method of manufacturing an OLED display device, a mask, and a method of designing the mask.
Organic light-emitting diode (OLED) elements are current-driven self-light-emitting elements. For this reason, the OLED elements are advantageous in the points such as elimination of backlight, low power consumption, wide viewing angle, and high contrast ratio, which promises the development of flat panel display devices.
There are two types of OLED display devices: one is color filter type that produces three colors of red (R), green (G), and blue (B) from white OLED elements with color filters and the other is selective deposition type in which organic light-emitting materials for the three R, G, B colors are separately applied. The color filter type has a disadvantage of high power consumption because the color filters absorb light to lower the light usage rate. In contrast, the selective deposition type has advantages of high color purity to easily produce a wide color gamut and no color filters to achieve high light usage; accordingly, the selective deposition type is widely employed.
Manufacturing the selective deposition type of OLED display device uses sheet-like metal masks (called fine metal masks (FMM)) to selectively apply organic light-emitting materials for individual colors. An organic light-emitting material is applied (vapor deposited) to form a film through openings provided in a metal mask. The metal mask deforms easily because of its structure; particularly, as the metal mask becomes thinner and larger to achieve higher definition and larger screen in the OLED display device, the metal mask deforms more easily. Hence, a problem has arisen that selectively applying organic light-emitting materials with high precision is difficult.
In order to solve the problems such as brightness defect and color mixture, JP 2004-30975 A discloses a method of designing an appropriate mask including a tolerance for the actual non-uniformity of the metal mask for organic electronic light-emitting elements.
The manufacturing an OLED display device according to JP 2004-30975 A deposits an organic light-emitting material from a fixed evaporation source onto the substrate. To deposit an organic light-emitting material in manufacturing an OLED display device, there is a known way using a linear evaporation source (also simply referred to as linear source) having linearly-disposed multiple nozzles, instead of a fixed evaporation source.